There are basically three types of mountain bicycle rims available today. These rim types are depicted by their spoke configuration. They include: a) individual wire spokes, hereafter referred to as the Type I design, b) integral rim/spoke design and c) solid disc (no spokes). The most common rim type is the Type I design (individual wire spokes). This disclosure applies to the Type I rim. FIG. 1 illustrates a Type I wheel assembly, and the associated components. The assembly consists of the rim (1) connected to a hub (3) by a system of spokes (2). The spokes are usually made from a stainless steel material configured with a hook at the hub end and a threaded, adjustable part (spoke nipple) at the rim end. This arrangement allows the individual spokes to be adjusted to a pre-tension load (PTL). These tension loads create a hoop tension load (HTL) in the hub and a hoop compression load (HCL) in the rim. After installation, the stress field within the wheel assembly causes the entire assembly to behave as a unit, allowing it to support both radial and lateral loads. The spoke system is not considered part of the invention, but is presented here to explain the spoke accommodations required by the invention.
There is currently a demand for a high performance bicycle wheel rims for the off-road competition environment. These high performance rims require both high strength and high stiffness at minimum weight (high strength-to-weight and stiffness-to-weight ratios). What sets this invention apart from other prior art designs is the use of unique, optimized section geometries that utilize the strength and stiffness properties of modern medium and high strength aluminum alloy materials to achieve superior strength-to-weight and stiffness-to-weight ratios. This invention has been evaluated against two leading bicycle rim designs, one representing one of the strongest and the other one of the lightest rims available on the market. This evaluation was made using a high resolution finite element computer modeling system. The results of this study are presented herein in support of this invention.